/***
 * Copyright 2002-2010 jamod development team
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ***/

package net.wimpi.modbus.io;

import java.io.IOException;

import net.wimpi.modbus.ModbusIOException;
import net.wimpi.modbus.msg.ModbusMessage;
import net.wimpi.modbus.msg.ModbusRequest;
import net.wimpi.modbus.msg.ModbusResponse;

/**
 * Interface defining the I/O mechanisms for <tt>ModbusMessage</tt> instances.
 * 
 * @author Dieter Wimberger
 * @version @version@ (@date@)
 */
public interface ModbusTransport {

	/**
	 * Closes the raw input and output streams of this <tt>ModbusTransport</tt>.
	 * <p>
	 * 
	 * @throws IOException
	 *             if a stream cannot be closed properly.
	 */
	public void close() throws IOException;

	/**
	 * Writes a <tt<ModbusMessage</tt> to the output stream of this
	 * <tt>ModbusTransport</tt>.
	 * <p>
	 * 
	 * @param msg
	 *            a <tt>ModbusMessage</tt>.
	 * @throws ModbusIOException
	 *             data cannot be written properly to the raw output stream of
	 *             this <tt>ModbusTransport</tt>.
	 */
	public void writeMessage(ModbusMessage msg) throws ModbusIOException;

	/**
	 * Reads a <tt>ModbusRequest</tt> from the input stream of this
	 * <tt>ModbusTransport<tt>.
	 * <p>
	 * 
	 * @return req the <tt>ModbusRequest</tt> read from the underlying stream.
	 * @throws ModbusIOException
	 *             data cannot be read properly from the raw input stream of
	 *             this <tt>ModbusTransport</tt>.
	 */
	public ModbusRequest readRequest() throws ModbusIOException;

	/**
	 * Reads a <tt>ModbusResponse</tt> from the input stream of this
	 * <tt>ModbusTransport<tt>.
	 * <p>
	 * 
	 * @return res the <tt>ModbusResponse</tt> read from the underlying stream.
	 * @throws ModbusIOException
	 *             data cannot be read properly from the raw input stream of
	 *             this <tt>ModbusTransport</tt>.
	 */
	public ModbusResponse readResponse() throws ModbusIOException;

	/**
	 * Flushes any data waiting to be read from this transport. Discards any
	 * waiting data.
	 */
	public void flush();

}// class ModbusTransport
